Each team is allowed 13 players, with seven (a goalkeeper and six field players) participating at any one time. Except for the goalkeeper, players may handle the ball with only one hand. The game is usually played in four quarters, each quarter being eight minutes in length with two minute intervals between quarters (32 minutes of stopped time). Substitutions are most common after a goal is scored, between periods, or for an ejected player. Each team is allowed two time outs within a match. Physical contact is the rule rather than the exception, as the players manoeuvre for position in front of the goal. A goal (1 point) is scored when the ball is thrown or pushed completely past the face of the goal.
There are two types of fouls in water polo -- ordinary fouls, which account for approximately 90 percent of the whistles during the game, and major fouls. Players are allowed three major fouls before they foul out of the match. Major fouls include exclusion and penalty fouls.
Common ordinary fouls include:
* Touching the ball with two hands
* Taking the ball under water when tackled
* Impeding an opponent who is not holding the ball
* Pushing off an opponent
When the referee calls an ordinary foul, the offended team is awarded a free throw at the point of the foul. The offended team must put the ball in play within three seconds by releasing, swimming or passing the ball. A player can only shot the ball if at least five meters away from the goal.
Common exclusion fouls include:
* Kicking or striking;
* Deliberate splashing in the face;
* Interfering with a free throw;
* Misconduct or disrespect to the referee;
* Holding, sinking or pulling back an opponent not holding the ball.
* Exclusion fouls result in a player being excluded for 20 seconds.
The excluded player (or his/her substitute) may not return until the 20 second exclusion time expires, a goal is scored or a change of possession takes place, whichever occurs first. A player with three major fouls is removed from the game with substitution. Deliberate kicking or striking with intent to injure (brutality) results in ejection of the offending player for the remainder of the game, substitution allowed after 4 minutes. Penalty fouls are committed within the five-meter area where a goal probably would have resulted. The offensive player fouled while in control of the ball and facing the goal inside the five-meter line is usually awarded the penalty throw. A penalty foul is recorded against the player committing the foul. The shot is taken from the five-meter line, with only the goalie defending